Re: About diagonal matrices

[John W. Eaton]

On 20-Feb-2009, Jaroslav Hajek wrote:

| I think that what Octave does now for sparse * scalar is certainly
| better than what Matlab does; I'd keep it that way. Otherwise, when
| you do scalar * sparse, and just by coincidence scalar happens to be
| Inf or NaN, you fill up the memory; bang, you're dead (or your
| computation is).
| 
| Note that Matlab is not strictly numerically consistent either; try
| "speye (3) * [NaN; 1; 1]" vs. "eye (3) * [NaN; 1; 1]".
| There is simply a difference between a "numeric zero" and "assumed
| zero" (or "defined zero"). The second one just always nullifies, which
| is what the user actually expects.
| I'd say document this somewhere, but keep the assumed zeros. IMHO
| these are really corner cases and we do not need to copy the less
| intelligent behavior of Matlab just for compatibility.

I agree that these cases don't come up all that often.  So why not
give the correct answer when they do?

jwe